All rules are to be taken as Tenhou standard for East-South, ari-red-fast. New is the last tenpai-yame addition.

Late penalty: -6 per full 5 minutes, distributed to your opponents after the normal game score.
Warned absence: -19 points, distributed to every player +1 (delta = -20 pt). The reason for this is to encourage presence, break close ties for people present more often, but also as an insurance policy against unwarned absences. Games will be re-seeded in such a case or subbed given my available options.
Unwarned absence: After 30 minutes, -90 points. We will find a sub to play in your place, your opponents will get +10 each for having to put up with a no-show, and everyone else +5. (Final numbers here subject to modification.)